Pneumatic compacting tool

ABSTRACT

In a pedestal type of compaction tool a pneumatic power transmitting connection between a reciprocating drive plunger and a vibratory compacting shoe is established by means of an air spring which is cyclically collapsed and extended in response to back and forth movement of the plunger relative to the compacting shoe. The resonant frequency and amplitude of the compacting shoe vibrations may be varied by increasing and decreasing the pressure to which the air spring is inflated.

United States Patent 1191 Opderbeck et al. Aug. 27, 1974 [54] PNEUMATIC CONIPACTING TOOL 3,421,377 l/l969 Wittig l73/l 18 X 3,489,228 I 1970 N Inventors; P opderbek New Berlm; 3,749,506 6i1973 194 /13;

Horst H. Mattern, Milwaukee, both of Primary Examiner-Nile C. Byers, Jr. 73] Asgignyeeallgkg cqmqgafion Milwaukee: Attorney, Agent, or FirmJames E. Nilles Wis. 22 Filed: June 28, 1973 [57] ABSIRACT In a pedestal type of compaction tool a pneumatic [21] PP -F 374,672 power transmitting connection between a reciprocating drive plunger and a vibratory compacting shoe is 52 us. c1. 404/133, 173/118 established by means of an air Spring which is y 51 1m. 01. E01c 19/34 eelly eellapsed and extended in response v baek and [58] Field of Search 404/133; 173/116, 118 forth movement of the plunger relative to the pacting shoe. The resonant frequency and amplitude 5 References Cited of the compacting shoe vibrations may be varied by UNITED STATES PATENTS increasingand decreasing the pressure to which the 3,308,729 3/1967 Kestel 404/133 Spnng ls 3,388,753 6 1968 Bardwell 404 133 x 10 Chums, 7 Drawing Flglll'es K 2 I 6 l l e o 11 9 II a 13 28 1 27 12 x 26 24 I '23 14 2 4 g PATENILU mi: 7 m4 SHEET 2 ll 5 PATENIEU 3.832.081

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PNEUMATIC COMPACTING TOOL BACKGROUND OF THE INVENTION The invention relates to compacting equipment such as ramming and tamping tools, and it is concerned more particularly with a mechanism for reciprocating the vibratory compacting member of such tools.

Vibratory compacting equipment has heretofore been known, wherein up and down acting thrust forces are developed by means of rotating excentric weights and wherein such thrust forces are transmitted directly to the compacting member of the equipment. In another heretofore known type of compacting equipment, a rotary crank is connected to an up and down movable plunger and the reciprocating movement of the plunger is mechanically transmitted to the vibratory compacting member usually by means of a steel spring assembly reacting between the plunger and the compacting member.

Both of the mentioned types of equipment, that is the inertia operated and the crank operated type, are commohly used for tamping, ramming and similar operations. However, as heretofore developed, the crank operated type has not been entirely satisfactory in certain practical respects, particularly in the manner of adapting the tool to prevailing work requirements by varying its resonant frequency and the coincident amplitude of its vibratory compacting member.

SUMMARY OF THE INVENTION The invention provides an improved compacting tool of the type wherein the vibratory compacting member is yieldingly coupled to a power driven reciprocating actuating element.

More particularly, the improved tool according to the invention incorporates an air spring which connects the power driven reciprocating actuating element in pneumatic power transmitting relation with the vibratory compacting element.

The invention further provides an improved compacting tool of the above mentioned character which may readily be adapted to prevailing working conditions by varying its resonant frequency and consequently the amplitude of the vibrating compacting element. To that end, the invention contemplates the provision of valve means for selectively increasing and decreasing pressure to which the air spring is inflated, an increase in the air pressure being effective to increase the resonate frequency and decrease the amplitude of vibration, and a decrease of the air pressure having the opposite effect.

The invention further provides an improved compacting tool of the above outlined character wherein the air spring not only connects the power driven actuating element in pneumatic power transmitting relation with the vibratory compacting element, but also hermetically seals the connection between compacting element and the main body of the tool against dust and dirt usually present at the working site for the tool.

The foregoing and other objects and advantages of the invention will become more fully apparent from the embodiments shown in the accompanyingdrawings.

DRAWINGS FIG. 1 is a perspective view of a pedestal type rammer embodying the invention;

FIG. 2 is a vertical section of the pedestal part of the rammer shown in FIG. 1 and illustrates a lifting stroke of the actuating plunger;

FIG. 3 is a view similar to FIG. 2 and illustrates a compacting stroke of the actuating plunger;

FIG. 4 is a perspective view illustrating another embodiment of the invention;

FIG. 5 is a vertical section of the pedestal part of the rammer shown in FIG. 4; and

FIGS. 6 and 7 are views similar to FIG. 5 on a reduced scale and illustrate-a lifting stroke and a compacting stroke, respectively, of the actuating plunger.

DETAILED DESCRIPTION The principal components of the rammer shown in FIG. 1 are a main frame 1; a power driven, vertically reciprocating actuating element 2 operatively mounted on the main frame 1; a vibratory compacting member 3 operatively mounted on the main frame 1 for back and forth movement relative to the actuating element 2; and pneumatically inflated flexible casing means in the form-of an air spring 4operatively interposed in pneumatic power transmitting relation between the actuating element 2 and the compacting member 3.

The main frame 1 comprises a generally cylindrical horizontal gear casing 6 and a drum shaped vertical casing 7 which is connected in depending position to the forward end of the gear casing 6. As shown in FIG. 2, the drum casing 7 has a central cylinder portion 8 which is flanged to the underside of the gear casing 6 by a circular series of cap screws 9. A horizontal top plate 11 and a bottom plate 12 of the casing 7 extended radially from the cylinder section 8-in vertically spaced relation to each other. A peripheral wall 13 connects the upper and lower plates 11 and 12 at their outer pe ripheries. Y

The power driven actuating element'2 comprises a plunger 14 which is slidably mounted for up and down reciprocating movement within the cylinder 8. The plunger 14 has a cylindrical recess extending upwardly from its lower end and a solid end portion 16. A diagonal wrist pin 17 is mounted in the end portion 16 of the plunger 14 and extends through the lower end of an up and down movable connecting rod 18 which is pivoted at its upper end to a rotatable crank shaft, not shown, in the gearing casing 6. An internal combustion engine 19 is mounted on the rear end of the gear casing 6 and is connected to conventional gearing, not shown, within the casing 6 for transmitting up and down movement to the plunger 14 through theconnecting rod 18. Also mounted on the gear casing 6 is a handle assembly 21 for manipulating the tool in the usual manner. The handle assembly 21 also mounts a fuel supply tank 22 for the engine 19,

A rammer shoe forming the compacting member 3 is reciprocably connected with the drum housing 7 by a pair of vertical guide rods 23 and 24 which are secured at the lower ends to the compacting member 3. The guide rod 23 is slidably fitted at its upper end into a guide bushing 26 on the plate member 12 of the drum housing 7. A shock absorbing coil spring 27 surrounds the upper ends of the guide rod 23 and reacts between the guide bushing 26 and a head 28 of the rod 23. The guide rod 24 is similarly connected to the housing 7 and located at the side of the cylinder 8 diametrically opposite to the guide rod 23.

The air spring 4 comprises an axially and radially deformable circumferential wall of flexible nonstretchable material such as rubber reinforced by fabric webbing. In the installed condition of the air spring 4 as shown in FIG. 2, the upper end of its circumferential wall is sealingly connected to the lower end of the plunger 14 by means of a flanged tubular spacer 29, and at its lower end the circumferential wall of the air bag 4 is connected to the compacting member 3 by a tubular flanged spacer 31. The circumferential wall of the air spring 4 has a beaded rim 32 at its upper end which is clamped air tight to the lower flange 33 of the spacer 29 by a circular series of cap screws 34. Similarly, the lower end of the circumferential wall of the air spring 4 has a beaded rim 34 which is clamped air tight to the upper flange 36 of the spacer 31 by a circular series of cap screws 37.

An air bag is thus defined by the circumferential wall of the air spring 4 and its connections with the plunger 14 and rammer shoe, and that air bag is pneumatically inflated to a suitable pressure so as to establish a pneumatic power transmitting connection between the vertically reciprocating actuating element 2 and the vibratory compacting member 3. Valve means 38 for selectively increasing and decreasing the pneumatic pressure within the air spring 4'are provided on the lower flange 33 of the spacer 29. Such valve means may be preferably in the form of an ordinary pneumatic tire valve as used on automobiles.

FIG. 2 shows the plunger 14 at the end of its up stroke within the cylinder 8 and the air spring 4 in correspondingly expanded condition. Downward move-'- ment of the plunger 14 from its lifted position to the lowered position in which it is shown in FIG. 3 compresses the air in the air spring 4 and thus transmits downward thrust upon the compacting member 3. Continuous up and down reciprocation of the plunger 14 by operation of the internal combustion engine 19 causes cyclical collapse and extension of the air spring 4 and thereby vibratory movement of the compacting member 3. The interconnected compacting member 3 and air spring 4 constitute an oscillating spring-mass system whose resonant frequency is determined by the spring constant of the air spring. In as much as the spring constant of the air spring is determined by the air pressure therein, the resonant frequency and the amplitude of the compacting member 3 can therefore readily be adjusted to the prevailing work requirements by increasing or decreasing the pressure to which the air spring 4 is inflated. Obviously. an increase of that pressure by means of the valve 38 will increase the resonant frequency of the system and correspondingly, reduce the amplitude of vibration; and on the other hand, a decrease of the inflated pressure of the air spring 4 by means of the valve 38 will decrease the resonant frequency and correspondingly increase the amplitude of vibration of the compacting member 3.

The rammer shown in FIG. 4 comprises the same upper structure 'as the rammer shown in FIG. 1, the same components being designated by the same reference characters in both views. However, instead of using one air spring 4, the rammer shown in FIG. 4 uses two air bags 39 and 41 for transmitting vibratory energy to the compacting member 3. As shown in FIG. 5,- an open ended cylinder 42 is flanged in a vertically depending position to the gear casing 6 by a circumferential series of cap screws 43. A drum housing 44 below the gear casing 6 comprises an upper plate member 46 extending radially from the cylinder 42 and a circumferential wall 47 flanged to the plate 46 by a circumferential series of cap screws 48. A second open ended cylinder 49 is supported by a bottom plate 51 of the drum housing 44 in axial alignment with the cylinder 42 and at a fixed axial spacing. therefrom. The bottom plate 51 of the drum housing 44 is secured at its periphery to the housing wall 47 by a circumferential series of cap screws 52.1Slidably mounted within the upper cylinder 42 for up and down movement therein by the crank operated connecting rod 18 is a plunger 53 which is axially recessed from its lower end. An annular packing 54 seals the plunger'53 within the cylinder 42. A second plunger 56 is slidably mounted within the cylinder 49 for vertical up and down movement relative to the drum housing 44. The plunger 56 is generally tubular and provided with a hollow mounting head 57 at its lower end for connection to the compacting member 3. The air bag 39 is similar to the air bag 4 shown in FIGS. 2 and 3 and is connected at its upper end in hermetically sealed relation to a flange 58 of the upper plunger 53 by a circumferential series of clamping bolts 59. The lower end of the air bag 39 is connected in hermetically sealed relation to the bottom plate 51 of the drum housing 44 by a circumferential series of clamping bolts 61.

l The second air bag 41 is also similar to the air bag 4 in FIGS. 2 and 3 and has a beaded upper rim which is secured in hermetically sealed relation to a radial flange 62 of the lower cylinder 49 by a circumferential series of clamping bolts 63. The lower end of the air bag 41 has a beaded rim by means of which it is connected in hermetically sealed relation to a radial flange 64 of the plunger head 57 by means of a circumferential series of clamping bolts 66. The air bags 39 and 41 are pneumatically interconnected through an air passage 67 in the flange 64 of the plunger head 57, the air passage 67 communicating at one end with the interior of the air bag 41 and at its other end with the interior of the plunger head 57, which in turn communicates with the interior of the air bag 39 through the tubular interior of the plunger 56. A cover 68 closes the lower end of the plunger head 57.

Like the air spring 4 of FIGS. 1 3, the air bags 39 and 41 of FIGS. 5 7 are pneumatically inflated to a suitable pressure so as to establish a pneumatic power transmitting connection between the vertically reciproeating actuating element 53 and the vibratory compacting member 3.

FIG. 6 shows theplunger 53 at the end of the upward stroke and the air bag 39 in correspondingly expanded condition. The lower plunger 56, in the condition of the mechanism as shown in FIG. 6, is also positioned at the upper end of its upward stroke which places the lower air bag 41 into a correspondingly collapsed condition. Movement of the upper plunger 53 from its raised posi tion in which it is shown in FIG. 6 to the lowered position in which it is shown in FIG. 7 causes a substantial portion of the air in the bag 39 to be pumped through the interior of the plunger 56 and the air passage 67 into the interior of the air bag 41 which is thereby placed into the expanded condition in which it is shown in FIG. 7. Continuous up and down movement of the plunger 53 cyclically expands and collapses the air bags 39 and 41 and thereby transmits vibratory power to the compacting member 3.

Valve means 38 are connected to the plunger head 57 for increasing and decreasing the pressure to which the air bags 39 and 41 are inflated. As explained here-. inbefore, in connection with FIGS. 2 and 3 an increase of the air pressure within the air bags 39 and 41 increases the resonant frequency and decreases the amplitude of the oscillating system comprising the air bag 41 and the plunger 56 and attached compacting member 3. Conversely, a decrease of the air pressure within the air bags 39 and 41 decreases the resonant frequency and increases the amplitude of the oscillating system.

Functionally, the upper cylinder 42* and plunger 53 in FIGS. 5 7 serve as a master cylinder and plunger assembly for a slave cylinder and piston assembly comprising the lower cylinder 49 and plunger 56. The drum housing 44 provides a hermetically sealed enclosure for the sliding connection between the master cylinder 42 and master plunger 53; and the air bags 39 and 41 provide a hermetically sealed enclosure for the sliding connection between the slave cylinder 49 and slave plunger 56.

We claim:

1 A pneumatic compacting tool comprising a main frame, a'power driven reciprocating actuating element operatively mounted on said main frame, a vibratory compacting member operatively mounted on said main frame for back and forth movement relative to said actuating element, pneumatically inflated flexible casing means operatively interposed in pneumatic power transmitting relation between said actuating element and said compacting member, and valve means operatively associated with said casing means for selectively increasing and decreasing the pneumatic pressure within said casing means.

2. A pneumatic compacting tool as set forth in claim 1, wherein said casing means comprise an air bag having opposite end portions sealingly connected, respectively, to said reciprocating actuating element and to said vibratory compacting member.

3. A pneumatic compacting tool as set forth in claim 2 wherein said air bag comprises an axially and radially deformable circumferential wall of flexible, nonstretchable material.

4. A pneumatic compacting tool comprising a main frame, power transmitting means operatively mounted on said main frame including a stationary open ended cylinder and a plunger reciprocable within said cylinder and projecting axially from one end thereof; a vibratory compacting member operatively mounted on said main frame in back and forth movable relation to said plunger in the axial direction of said cylinder; pneumatically inflated flexible casing means operatively interposed in pneumatic power transmitting relation between said projecting plunger end and said compacting member, and a pneumatic tire type valve operatively associated with said casing means.

5. A pneumatic compacting tool as set forth in claim 4 and further comprising a pair of guide rods slidably connecting said compacting member with said main frame at diametrically opposite sides of said cylinder.-

6. A pneumatic compacting tool comprising a main frame; a power driven reciprocating actuating element operatively mounted on said main frame; a vibratory compacting member operatively mounted on said main frame for back and forth movement relative to said actuating element; a first air bag operatively mounted in collapsible and extendable condition between said actuating element and said main frame; a second air bag operatively mounted in collapsible and extendable condition between said main frame and said compacting member; said first and second air bags being pneumatically interconnected and inflated so as to provide a pneumatic power transmitting connection between said actuating element and said compacting member.

7. A pneumatic compacting tool as set forth in claim 6 and further comprising a valve means operatively associated with the interior of said air bags for selectively increasing and decreasing the air pressure therein.

8. A pneumatic compacting tool comprising a main frame, a master cylinder and a slave cylinder mounted co-axially on said main frame at a predetermined spacing from each other, a power driven master plunger reciprocable with in said master cylinders and having an end portion projecting therefrom toward said slave cylinder, a slave plunger reciprocable within said slave cylinder and having. an end portion projecting therefrom away from said master cylinder, a vibratory compacting member operatively connected with said projecting end portion of said slave plunger; a first air bag mounted in collapsible and extendable condition between said projecting end of said master plunger and said main frame; and a second air bag operatively mounted in collapsible and extendable condition between said slave cylinder and said projecting end of said slave plunger; said first and second air bags being pneumatically interconnected and inflated so as to provide a pneumatic power transmitting connection between said master and slave plungers.

9. A pneumatic compacting tool as set forth in claim 8, wherein said slave plunger comprises an open end tubular portion reciprocably mounted within said slave cylinder, and a hollow head at said projecting end thereof in communication with the interior of said second air bag.

10. A pneumatic compacting tool as set forth in claim 9 and further comprising valve means connected to said hollow head of said slave plunger for selectively increasing and decreasing the pneumatic pressure within said first and second air bags. 

1. A pneumatic compacting tool comprising a main frame, a power driven reciprocating actuating element operatively mounted on said main frame, a vibratory compacting member operatively mounted on said main frame for back and forth movement relative to said actuating element, pneumatically inflated flexible casing means operatively interposed in pneumatic power transmitting relation between said actuating element and said compacting member, and valve means operatively associated with said casing means for selecTively increasing and decreasing the pneumatic pressure within said casing means.
 2. A pneumatic compacting tool as set forth in claim 1, wherein said casing means comprise an air bag having opposite end portions sealingly connected, respectively, to said reciprocating actuating element and to said vibratory compacting member.
 3. A pneumatic compacting tool as set forth in claim 2 wherein said air bag comprises an axially and radially deformable circumferential wall of flexible, non-stretchable material.
 4. A pneumatic compacting tool comprising a main frame, power transmitting means operatively mounted on said main frame including a stationary open ended cylinder and a plunger reciprocable within said cylinder and projecting axially from one end thereof; a vibratory compacting member operatively mounted on said main frame in back and forth movable relation to said plunger in the axial direction of said cylinder; pneumatically inflated flexible casing means operatively interposed in pneumatic power transmitting relation between said projecting plunger end and said compacting member, and a pneumatic tire type valve operatively associated with said casing means.
 5. A pneumatic compacting tool as set forth in claim 4 and further comprising a pair of guide rods slidably connecting said compacting member with said main frame at diametrically opposite sides of said cylinder.
 6. A pneumatic compacting tool comprising a main frame; a power driven reciprocating actuating element operatively mounted on said main frame; a vibratory compacting member operatively mounted on said main frame for back and forth movement relative to said actuating element; a first air bag operatively mounted in collapsible and extendable condition between said actuating element and said main frame; a second air bag operatively mounted in collapsible and extendable condition between said main frame and said compacting member; said first and second air bags being pneumatically interconnected and inflated so as to provide a pneumatic power transmitting connection between said actuating element and said compacting member.
 7. A pneumatic compacting tool as set forth in claim 6 and further comprising a valve means operatively associated with the interior of said air bags for selectively increasing and decreasing the air pressure therein.
 8. A pneumatic compacting tool comprising a main frame, a master cylinder and a slave cylinder mounted co-axially on said main frame at a predetermined spacing from each other, a power driven master plunger reciprocable with in said master cylinders and having an end portion projecting therefrom toward said slave cylinder, a slave plunger reciprocable within said slave cylinder and having an end portion projecting therefrom away from said master cylinder, a vibratory compacting member operatively connected with said projecting end portion of said slave plunger; a first air bag mounted in collapsible and extendable condition between said projecting end of said master plunger and said main frame; and a second air bag operatively mounted in collapsible and extendable condition between said slave cylinder and said projecting end of said slave plunger; said first and second air bags being pneumatically interconnected and inflated so as to provide a pneumatic power transmitting connection between said master and slave plungers.
 9. A pneumatic compacting tool as set forth in claim 8, wherein said slave plunger comprises an open end tubular portion reciprocably mounted within said slave cylinder, and a hollow head at said projecting end thereof in communication with the interior of said second air bag.
 10. A pneumatic compacting tool as set forth in claim 9 and further comprising valve means connected to said hollow head of said slave plunger for selectively increasing and decreasing the pneumatic pressure within said first and second air bags. 